In article ,
says...

wrote in message
ups.com...
In this new generation bicycle light system, no battery is needed, no
friction on any parts of the bicycle. The lights flash regardless speed
of the bicycle and weather conditions (unlike normal dynamos!). Very
bright.

It can be used as a stand-alone light system (as a normal dynamo) on
your bike, or used as a back-up for your existed battery-powered
lights.

There are DIY kits of this dynamo.

All details and buy on-line: http://www.freelights.co.uk


This bits impressive! "No drag can be detected in this device; it is not a
traditional dynamo. With this innovative, electrical generating system you
will not feel any extra weight when you are cycling. "

No drag = no power transfer = no electrical power generated; QED

Perpetual motion? I recall hub dynamos which didn't rely on friction
drive.

Unfortunately they didn't put out enough power, especially at low speed.
You could see the lamps flicker as they turned :-)
Bottom-bracket mounted dynamos are pretty good as they don't scrub like
the sidewall-driven ones can, but they can be prone to slipping and/or
rapid wear because the back tyre dumps loads of crap on them. You can
get toothed-belt drive dynamos that are driven by a pulley attached to
the side of the hub. A properly set up high-quality sidewall-driven
dynamo can still work pretty well anyway.